(1) Field of the Invention
The present invention relates to a strip-type piezoelectric resonator comprising a piezoelectric material such as lithium tantalate (LiTaO.sub.3) or the like and to a method for producing the same.
(2) Description of the Prior Art
Piezoelectric resonators comprise a plate of piezoelectric material, such as crystal or lithium tantalate, and a pair of electrode films coated on the upper and lower main surfaces of the plate. When an alternating current (a.c.) electric field is applied between the electrode films, the piezoelectric plate is subject to stress of a frequency equal to that of the a.c. electric field. When the frequency of the a.c. electric field coincides with the inherent resonance frequency of the piezoelectric plate, electric resonance occurs, resulting in greater oscillation of the piezoelectric chip. Oscillating devices comprising such piezoelectric resonators are widely used in oscillators or filters of communication apparatuses because of their compactness, high reliability and high stability of the oscillation frequency.
A prior art strip-type piezoelectric resonator comprising a resonator chip of a single crystal of LiTaO.sub.3 is illustrated in FIG. 1. The resonator 1 comprises an energy trapping-type piezoelectric resonator chip 4 housed in a cap 6 which is secured to a base 5. The piezoelectric resonator chip 4 comprises a strip-shaped chip plate 2 having a rectangular cross section and a pair of T-shaped electrode patterns 3 and 3' formed on the opposed two main surfaces (the front surface and the rear surface in the drawing) by an evaporation method. The piezoelectric resonator chip 4 is supported by a pair of support wires 7 and 7' which are secured to lead terminals 8 and 8', respectively. The lead terminals 8 and 8' are secured to the base 5.
The piezoelectric resonator of the prior art is high, and the support member for the resonator chip does not withstand vibration well. Also, assembly of the parts of the piezoelectric resonator of the prior art is troublesome. In order to decrease the height of the resonator, it has been proposed to fold the lead terminal 13, illustrated in FIG. 2, after the resonator 11 is mounted on a printed board 12. However, such an arrangement requires a large amount of space on the printed board.